Ethynylation of 17-keto steroids having a normal configuration at C.sub.14 generally proceeds by attack of the reagent at the sterically less hindered .alpha.-side of the keto group which results almost exclusively in the production of the 17.alpha.-ethynyl-17.beta.-ol derivative. Steroidal products resulting from attack at the 17.beta.-side of the keto group have been reported, but the yields of these compounds generally have been very low. By means of the present invention, a novel process for the preparation of 17.beta.-ethynyl-3,17.alpha.-estradiol and derivatives thereof is provided.